Hydraulic lift



J. L. CROLL HYDRAULIC LIFT May 17, 1960 2 Sheets-Sheet 1 Filed Oct. 12, 1956 fl a myw INVENTOR bk/I L. C'ral/ avg a Af/ar/zJ J United States Patent HYDRAULIC LIFT John L. Croll, Kansas City, Kans.

Application October 12, 1956, Serial No. 615,612

2 Claims. (Cl. 254-9 3 "lazy Susan linkage 20, comprising a double set of links at each side of the bed. The links of one of said sets are designated by the numeral 32, and are joined successively at their contiguous ends by pivots 34. The links are disposed in zig-zag relation. The links of the other set are designated by the numeral 36, and are joined successively at their contiguous ends by pivots 38. Links 36 are also disposed in zig-zag relation, and so disposed that each link intersects the corresponding link 32, and is pivoted thereto at 40; Pivots 34, 38 and 40 are all parallel, and are formed by shafts extending between the double sets of links at each side of the bed and serving as pivotal members for both of said link-sets, thereby. imparting rigidity to the linkages at right angles to their plane. The link sets at opposite sides of the bed are held spaced apart by spacer sleeve 42 carried on the pivot shafts34.

The lower ends of the. lowermost links 32 are journalled on a shaft 44 parallel to pivots 34, 38 and 40 and mounted in bearings 46 fixed to the upper surface of bed 4. The

upper ends of the uppermost links 32 are journalledon its space requirements, in order to facilitate mounting thereof on truck beds or other mobile vehicles. A further object is the provision of a lift of the character described having novel means for levelling the bed thereof so that the lift may function in a truly vertical line, thereby facilitating use of the lift on mobile vehicles which may rest on sloping or uneven terrain.

Other objects are simplicity and economy of construction, and efuciency and dependability of operation.

With these objects in view, as well as other objects which will appear in the course of the specification, reference will be had to the drawing, wherein:

Fig. 1 is a side elevational view of a hydraulic lift embodying the present invention, shown in a partially raised position,

Fig. 2 is a sectional view taken on line IIII of Fig. 1, with parts broken away,

Fig. 3 is a sectional view taken on line IIIIII of Fig. l, and

Fig. 4 is a foreshortened sectional view taken on line IV-IV of Fig. 1.

Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies to. a planar base which obviously could be supported either directly on the ground or floor, or on the bed of a truck, trailer, or other mobile vehicle. A planar bed 4 is disposed above and generally parallel to the base. Disposed between the base and the bed' is a generally crossshaped pivot member 6 having a stub axle at each of the four extremities thereof. One opposite and coaxial pair of said axles, designated by the numerals 8 and 10, are journalled in bearings 12 affixed to base 2. The other pair of axles 14 and 16 are disposed coaxially to each other and at right angles to axles 8 and 10, are journalled in bearings 18 affixed to the lower surface of bed 4.

Bed 4 may be adjustably tilted about axles 14 and'16 of pivot member 6 by means of a bolt 20 secured in member 6 adjacent axle 8 and extending upwardly through said bed. Said bolt is provided with a pair of lock nuts 22 disposed respectively above and below the bed. Pivot member 6 may be tilted relative to base 2, about axles 8 and 10, by means of a bolt 24 secured in base 2 and extending upwardly through member 6 adjacent axle 14. Said bolt is provided with a pair of lock nuts 26 disposed respectively above and below member 6. It will thus be apparent that by adjusting bolts 20 and 24, bed 4 may be tilted universally with respect to the base, and may therefore be levelled accurately despite the fact that the base, or the vehicle supporting said base, may be resting on uneven or sloping terrain.

A platform 28 is supported above bed 4 by a double a shaft 48 mounted in bearings 58 afiixed to the lower surface of platform 28. The lower ends of the lowermost links 36 are journalled on a shaft 52 which is parallel to shaft 44. Rotatably mounted on each end of shaft 52 is a roller 54 said rollers being operable to roll along the upper surface of bed 4 respectively at opposite edges thereof. Each of said rollers is retained against the bed by a keeper 56 affixed to the bed. The upper ends of the uppermost links 36 are similarly journalled on a shaft 58 on which are rotatably mounted rollers 60 which engage the lower surface of platform 28 and are retained against said platform by keepers 62 affixed to the platform. I

It will be apparent that if shaft 52 carrying rollers 54 is moved horizontally toward shaft 44, the linkage 30 will be vertically extended, thereby elevating platform 28 to a greater height, and that if shaft 52 is moved farther away from shaft 44, the platform will be lowered. It will be obvious that platform 28 may carry workmen, supplies or equipment. Also, said platform could be fitted with lateral extensions, turntables and the like if desired. Such equipment, however, forms no part of the present invention and is not shown.

The equipment for moving shaft 52 horizontally as described is hydraulic, and is best shown in Fig. 2. It includes a pair of cylinders 64 which are parallel and coextensive, and disposed horizontally at right angles to shaft 52. They are each pivoted at 66 to brackets 68 fixed to bed 4. Each of said cylinders is provided with a piston 70 and a piston rod 72. The extended ends of said piston rods are aflixed respectively to the oppositely extended ends 74 of a U-shaped member 76 which rests slidably on bed 4 between cylinders 64. A third cylinder 78 is pivoted at 80 to the central portion of member 76, and is parallel to and longitudinally coextensive with cylinders 64. Cylinder 78 is provided with a piston 82 and piston rod 84, the outer end of said piston rod being; fixed to a head 86 journalled on shaft 52 at the midpoint thereof. Each of cylinders 64 and 78 are'provided with a hose connection 88 through which fluid under pressure from any suitable source, not shown, may be supplied to said cylinders.

The operation of the lift is believed apparent from theforegoing description. The arrangement of cylinders 64* and 78 effects a valuable economy in space requirements,. since the effective travel of head 86 is thereby rendered approximately double the length of the longitudinal spacerequired for the cylinders. This economy is particularly" important where the lift is to be mounted on a truck bed: or in other spaces of limited size, since it permits the:

use of a platform and lifting linkage of maximum horizontal area.

While I have shown and described a specific embodiment of my invention, it will be apparent that many minor changes of structure and operation could be made without departing from the spirit of the invention as de-'- fined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent is: x

1. A hydraulic lift comprising a planar bed adapted to be supported by a mobile vehicle, a vertically extensible linkage secured at its lower end to said bed, said linkage including a member operable by linear movement to extend said link-age, a planar platform secured to the upper end of said linkage, and hydraulic means carried by saidbed and operable to extend said linkage, said linkage being retractable by gravity, said hydraulic means com prising a first hydraulic cylinder parallel to the direction 2. A hydraulic lift comprising a planar bed adapted to be supported by a mobile vehicle, a vertically extensible linkage secured at its lower end to said bed, said linkage including a member operable by linear movement to extend said linkage, a planar platform secured to the upper end of said linkage, and hydraulic means carried by said bed and operable to extend said linkage, said linkage being retractable by gravity, said hydraulic means comprising a first hydraulic cylinder parallel to the direcof movement of said linkage member, said cylinder being fitted with a piston and a piston rodconnected to said linkage member, a second hydraulic cylinder parallel to and normally longitudinally coextensive with said first cylinder, said second cylinder being attached to said bed and fitted with a piston and piston rod, and a rigid member attached to said first cylinder and to the piston rod of said second cylinder. 1

References Cited in'the file of this patent UNITED STATES PATENTS 163,838 Baker June 1, 1875 2,402,579 Ross June 25, 1946 2,449,049 Black Sept. 14, 1948 2,568,228 Forse Sept. 18, 1951 2,683,277 Bernaerts July 13, 1954 

